Handler is a feature to perform detailed scanning setting on a per request basis for the proxy log.
You can perform scanning for the complicated applications that cannot be handled by "Automatic scanning setting" in "Auto-Crawler" or in "Page Transition Diagram" since it can set the page transition order, change the submitted value, and hand over values from other pages.
There are three types of Handler:"Pre processor", "Extended processor", "Post processor".
Depending on the purpose of use, you should use properly either "Pre processor" , "Extended processor" or "Post processor".
＜Overview of Handler＞